1. Field of the Invention
The present invention relates to a battery including a cathode, an anode, and an electrolyte, in which the anode includes an anode active material layer.
2. Description of the Related Art
In recent years, many portable electronic devices such as combination cameras (videotape recorder), digital still cameras, mobile phones, personal digital assistants, and notebook personal computers have been widely used, and their size and weight have been reduced and their high performance and multifunction have been achieved. Accordingly, as a portable power source for the electronic devices, the high capacity of batteries, in particular rechargeable secondary batteries has been aspired, and research and development to improve the energy density of the secondary batteries has been actively promoted
Specially, secondary batteries (so-called lithium ion secondary batteries) in which a carbon material such as graphite is used for the anode, and a composite oxide of lithium (Li) and a transition metal is used for the cathode have been practically used widely, since such lithium ion secondary batteries can provide the higher energy density compared to existing lead batteries and nickel cadmium batteries. However, since the capacity of the lithium ion secondary battery is already close to the saturated state, it is extremely difficult to expect the largely increased capacity thereof in the future.
To attain the high capacity of the secondary battery, it has been considered to use a secondary battery (so-called lithium metal secondary battery) using dissolution and precipitation of lithium metal for charge and discharge reaction by using the lithium metal for the anode. However, in the lithium metal secondary battery, while the high capacity can be obtained, efficiency of dissolution and precipitation of lithium is not sufficient. In addition, the lithium metal is easily precipitated in the state of dendrite during the charge.
Therefore, recently, as an improved lithium ion secondary battery, a battery in which the simple substance, an alloy, or a compound of silicon (Si) or tin (Sn) is used for the anode has been actively considered. The theoretical capacity of such a battery system is 2000 mAh or more. In particular, in the case of using the simple substance of silicon, the theoretical capacity thereof reaches about 4000 mAh. Thus, such a lithium ion secondary battery is expected to have the largely increased capacity in the future.
In the field of developing the secondary batteries, not only the structure of the anode but also the structures of respective components of the battery have been considered in various manners. For example, it is proposed to use polyether sulfone as a binder for the cathode (for example, refer to Japanese Unexamined Patent Application Publication No. 2002-298915). Further, it is proposed that for the structure of the separator, a porous membrane including a basic solid particles and a composite binder (main binder and sub binder) is used, and polyether sulfone is used as the main binder (for example, refer to Japanese Unexamined Patent Application Publication No. 2004-273437).